EFFECTS ON ENDWALL HEAT TRANSFER BY A WINGLET VORTEX GENERATOR PAIR MOUNTED UPSTREAM OF A CYLINDER

Abstract

The present study was conducted to investigate heat transfer enhancement from the endwall of a protruding circular cylinder by addition of a winglet vortex generator pair. A steady-state liquid crystal thermography technique was employed. The vortex generator pair is installed upstream of a cylinder placed either in counter flow inward or counter flow outward orientation. The vortex generator installed in the counter flow inward orientation presented the best heat transfer. The effects of the vortex generator attack angle on the junction wall heat transfer are also investigated and the 45° yaw angle with respect to the streamwise direction provided higher thermal performance. The position of the vortex generator with respect to the cylindrical obstacle is swapped in the streamwise and spanwise directions to find out the appropriate location of the vortex generator regarding enhancement of endwall heat transfer. The results indicated that the effect of the vortex generator in enhancing the endwall heat transfer is prominent in the spanwise direction rather than in the streamwise direction. Up to 25% heat transfer enhancement has been found with a pressure drop penalty of 4.8%, thus giving high thermal performance. (Less)